1. Field of the Invention
The present invention is related to a build-up multilayer printed wiring board and a method for manufacturing such a multilayer printed wiring board; especially to a multilayer printed wiring board having a plane conductor and a method for manufacturing such a multilayer printed wiring board.
2. Discussion of the Background
In response to IC chips becoming more highly functional, a fine-pitch circuit structure is required for a printed wiring board forming a package substrate to mount electronic components such as an IC chip. Japanese Patent No. 3629375 describes that circuits be formed not by a conventional semi-additive method but by a laser. In such a circuit-forming method, concave portion (353b) for forming a circuit, opening 351 for forming a via conductor and concave portion (353a) for forming a plane conductor are formed as shown in FIG. 28(B) in interlayer resin insulation layer 350 shown in FIG. 28(A). Then, electroless plated film 352 and electrolytic plated film 356 are deposited in concave portion (353b) for forming a circuit, in opening 351 for forming a via conductor and in concave portion (353a) for forming a plane conductor as shown in FIG. 28(C). Accordingly, conductive circuit 358, via conductor 360 and plane conductor 359 are formed. The contents of this publication are incorporated herein by reference in their entirety.